Fluvial landforms (erosional)Watch
(I'm on aqa AS Level)
Spurs are ridges of hard, resistant rock which extend downwards from the top of the valley sides towards the river, also found along the upper course. The river is forced to flow around them, it does not have enough energy to laterally (horizontally) erode the hard rock. The spurs appear to interlock like the teeth of a zip, hence the name interlocking spurs.